Thermal monitoring system in an integrated circuit die

ABSTRACT

An integrated circuit die that includes a temperature monitoring system that obtains measured temperature data from on die temperature sensors during a mode when power is not being supplied to a system controller of the die. After the system controller is powered up, the system controller obtains the measured temperature data. This system and method can be useful in that heat from a powered up system controller does not affect the temperature readings of the temperature monitoring system.

BACKGROUND OF THE INVENTION Field of the Invention

This invention relates to a temperature monitoring unit for anintegrated circuit die.

Description of the Related Art

Integrated circuit die can include temperature monitoring systems fordetecting the temperature of the integrated circuit die. In someexamples, these circuits can be used to determine whether thetemperature is exceeding a predetermined threshold due to eitherinternal or external conditions. If due to internal conditions, theintegrated circuit can reduce operations to reduce the operatingtemperature or, if due to an external condition, provide warningsregarding the external condition.

In such examples, the temperature measured by the temperature monitoringsystem may have to be calibrated to account for variations in the die.In some examples, a subset of the integrated circuit die may be testedat known temperatures (e.g. such as in an oil bath) where the measuredtemperature can be compared with the actual temperature to developcalibration values to adjust the measured temperature reading to providea more accurate measurement.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may be better understood, and its numerousobjects, features, and advantages made apparent to those skilled in theart by referencing the accompanying drawings.

FIG. 1 is a block diagram of an integrated circuit die according to oneembodiment of the present invention.

FIG. 2 is a flow diagram of a temperature calibration operation by asystem according to one embodiment of the present invention.

FIG. 3 is a state diagram of the operation of a temperature monitoringsystem according to one embodiment of the present invention.

FIG. 4 is a flow diagram of an operation for determining calibrationvalues according to one embodiment of the present invention.

FIG. 5 is a flow diagram of a temperature monitoring operation by asystem according to one embodiment of the present invention.

The use of the same reference symbols in different drawings indicatesidentical items unless otherwise noted. The Figures are not necessarilydrawn to scale.

DETAILED DESCRIPTION

The following sets forth a detailed description of a mode for carryingout the invention. The description is intended to be illustrative of theinvention and should not be taken to be limiting.

In a system that includes a temperature monitoring system, thetemperature monitoring system and system controller are each located inindependently operable power domains. During a calibration operation ofthe temperature monitoring system, the power domain to the systemcontroller can be turned off so as to reduce or eliminate the effect ofthe operation of the system controller on the temperature measurementsmade during the calibration operation. During the calibration operation,temperature measurements made by the temperature monitoring system at aknown temperature are stored in a memory location in the temperaturemonitoring system. After the calibration operation, the data isaccessible to the system controller. The data can be used to generatecalibration values for adjusting temperature data subsequently taken bya temperature monitoring system.

With prior art temperature monitoring systems, calibration measurementsmade by the temperature monitoring system during a calibration operationmay be affected by heat generated by power being supplied to othercircuitry of the integrated circuit including the system controller.Even though the other circuitry may not be operating during thecalibration operation, heat can be generated by the other circuitry fromleakage current due to power being supplied to the other circuitry. Thisheat may affect the accuracy of the measurements made duringcalibration, and consequently may affect the accuracy of the calibrationvalues calculated from those measurements. Accordingly, providing asystem with independent power supply domains and performing acalibration operation while power is not supplied to the systemcontroller may provide, in some embodiments, an improved system thatgenerates more accurate temperature data.

FIG. 1 is a block diagram of a system 101 according to one embodiment ofthe present invention. In one embodiment, system 101 is implemented onan integrated circuit die 102. Integrated circuit die 102 is formed byprocessing a semiconductor wafer (not shown) to form circuitry on thesemiconductor wafer and then subsequently dicing the wafer intosemiconductor die. In some embodiments, system 101 is referred to as asystem on a chip (SOC) in that a system is implemented on the die. Insome embodiments, system 101 is characterized as a microcontroller, amicroprocessor, an embedded controller, or a motor control unit, butmaybe characterized as other systems or devices in other embodiments.System 101 includes a system controller 105, a system memory 107, systemperipherals 111, and a temperature monitoring system 104.

In one embodiment, system controller 105 is implemented with one or moreprocessor cores that execute code to perform functions of the system. Insome embodiments, system 101 is a CPU, microprocessor, DSP, or MCU.System memory 107 may include both volatile and non-volatile on diememory for storing code to be executed, data obtained or received,and/or data to be used in the operation of the system. For example,memory 107 includes calibration data 108 that is used to adjusttemperature data provided by the temperature monitoring system 104.

System 101 also includes one or more peripherals 111 such as externalbus controllers, voice monitoring circuitry, external memory interfaces,and driver circuitry such as graphics circuitry, keyboard controllers,and mouse controllers. System 101 may include a number of other devicesas well such as bus interface controllers. In some embodiments, system101 may be implemented in a number of different types of electronicsystems such as a computer system, a router, a smart phone, tablet,automobile, or embedded system. However, system 101 may be implementedin other types of electronic systems as well and may include othercircuitry specifically for those systems.

In the embodiment shown, the memory 107, peripherals 111, and interface115 are each shown connected to controller 105 with different systembusses. However, in other embodiments, these devices may be connected onthe same bus. Also, system 101 may have other configurations in otherembodiments.

System 101 includes a temperature monitoring system 104 for measuringthe temperature at various locations on die 102. Temperature monitoringsystem 104 is coupled to system controller 105 by a bus 113 andinterface 115. Temperature monitoring system 104 includes a controller121 that includes a memory (e.g. data register 131) for storing measuredtemperature data and a configuration register 132 for storingconfiguration information from the system controller 105 for controllingthe operation of controller 121 during its operations.

Controller 121 includes a calibration module 129. Calibration module 129is the portion of controller 121 that controls the operation of thetemperature monitoring system 104 during a calibration operation (assubsequently described). In one embodiment, module 129 is the mainprocessor circuitry of controller 121 that controls temperaturemonitoring system 104 during other operations as well. In otherembodiments, module 129 is implemented in hardware or firmware thatcontrols system 104 during the calibration operation. In still otherembodiments, module 129 is processing circuitry separate from theprocessing circuitry of controller 121 that controls system 104 duringother operations.

Interface 115 includes bus interface circuitry (not shown) forcommunicating with system controller 105 on bus 113 and forcommunicating with controller 121 on various signal lines. Interface 115includes a memory (configuration register 117) for storing theconfiguration information received from system controller 105 forpassing the information onto controller 121. The configurationinformation provided to controller 121 is for controlling the operationof controller 121. Interface 115 also receives commands from systemcontroller 105 for providing control signals to controller 121 toexecute handshaking protocols.

Temperature monitoring system 104 includes a number of signal lines forexchanging signals between interface 115 and controller 121. The READYsignal is provided by controller 121 to indicate that controller 121 isoperational and can communicate with the system controller 105. The VDD1READY signal indicates that power is being provided to the systemcontroller 105. The CONFIGURATION signal lines are used to provideconfiguration information to controller 121 that controller 121 uses inperforming its operations. The DATA signal lines are used to providemeasured temperature data to the system controller (via interface 115).The CALIBRATION START signal is an indication for controller 121 tostart the calibration mode of operation. The MONITORING START signal isan indication to controller 121 to start the monitoring mode ofoperation.

The CONFIGURATION signal lines, the CALIBRATION START signal line andthe MONITORING START signal line all include an isolation switch (161,163, and 165), respectfully that are made conductive with the assertionof the ENABLE signal by controller 121. Isolation switches 161, 163, and165 are utilized to place these signal lines at controller 121 in aknown state when the VDD1 power domain is off.

Temperature monitoring system 104 includes a power on reset (POR)circuit 125 for providing a RESET signal to controller 121 during powerup. System 104 also includes a clock circuit 123 which provides a clocksignal. In one embodiment, clock circuit 123 is a ring oscillator.

Temperature monitoring system 104 includes analog monitoring circuitry133 and temperatures sensors 137 and 139 for taking temperaturemeasurements on die 102. Sensors (137, 139) are located at variouslocations throughout die 102. In one embodiment, sensors 137, 139 arecharacterized as Bipolar Junction Transistor (BJT) type sensors whichproduce a voltage difference as a pair, that is indicative of thetemperature when injected by current from circuitry 133. Circuitry 133converts the voltage difference into a current.

Analog measurement circuitry 133 includes an analog to digital converter(ADC) 135 that receives the current indicative of the temperature asindicated by the sensors (137, 139) and converts it to a digital valuethat is provided on bus 136 to controller 121. In one embodiment,circuitry 133 includes a Proportional To Absolute Temperature (PTAT)Generator (not shown) that is coupled to one or more of the sensors(137, 139). The PTAT generator receives a control signal from controller121 via bus 138 and provides a current that is a function of thetemperature sensed by one of the sensors during a measurement operation.In some embodiments, circuitry 133 also includes a bandgap referencegenerator (not shown) that receives a control signal from controller 121and provides a reference current to ADC circuit 135 for use inconverting an analog signal to a digital value. A further explanationregarding an embodiment of analog measurement circuitry 133 and itsoperation for generating temperature data can be found in United StatesPatent Application entitled TEMPERATURE SENSOR CIRCUITRY AND METHODTHEREFOR, having a filing date of Nov. 28, 2016, having an applicationnumber of Ser. No. 15/362,092, having a common assignee, and havinglisted inventors Firas N. Abughazaleh and Venkata Rama Mohan ReddyMooraka, all of which is incorporated by reference herein in itsentirety. However, a temperature monitoring system may include othertypes of temperature sensors such as a MOSET type sensor and/or includeother types of analog temperature circuitry to provide a currentindicative of temperature such as in other embodiments.

System 101 includes two power domains. A power domain of a die is a partof a die that is powered from a power source with different powerdomains of a die being powerable from different power sources. In someembodiments, different power domains of a die may differ from each otherby one or more characteristics such as, e.g. having different voltagevalues, noise requirements, or operating states. In the embodimentshown, integrated circuit die 102 includes a VDD1 external terminal 141and a VDD2 external terminal 143 each for receiving power to supply totheir different power domains. In some embodiments, an external terminalcan be for example a pad, bump, ball, pin, or post for accessingcircuitry of the integrated circuit die. By providing two power supplyvoltage external terminals, each of the power domains can operateindependently with respect to each other on the integrated circuit die.

Terminal 141 supplies power to VDD1 regulator 147 which supplies aregulated VDD1 voltage to the system controller 105, system memory 107,peripherals 111, and interface 115. In the embodiment shown, VDD1regulator 147 does not increase or decrease the voltage level of thesupply voltage but may so in other embodiments.

Terminal 143 receive a supply voltage VDD2 and supplies that voltage toanalog measurement circuitry 133 and to voltage regulator 127. Voltageregulator 127 converts the VDD2 voltage to provide a regulated VDD3voltage which is different than the VDD2 voltage. In one embodiment,VDD2 is 1.8 volts and VDD1 and VDD3 is 0.8 volts.

Making power domain VDD2 and power domain VDD1 independent of each otheron the die enables the power domain of VDD1 to be completely off whentemperature monitoring system 104 is gathering temperature data during acalibration mode. The ability to remove power from power domain VDD1during a calibration mode removes the heat generated by the circuitry ofpower domain VDD1 from affecting the temperature readings duringcalibration.

System 101 also includes external access and interrupt terminals 171 and173. These terminals are utilized to provide and receive data fromsystem 101 externally and to generate external interrupts to the systemcontroller.

FIG. 2 shows an embodiment of a handshaking protocol 201 for theinitiation of the calibration mode by temperature monitoring system 104according to one embodiment of the present invention. Protocol 201begins with both VDD1 and VDD2 power domains being powered up inoperation 203. In operation 205, controller 121 asserts the READY signalon the READY signal line indicating that controller 121 is operational.In one embodiment, controller 121 asserts the READY signal by writing toan internal register (not shown) that is coupled the READY signal line.In operation 207, in response to the VDD1 READY signal being asserted byinterface 115, controller 121 asserts the ENABLE signal to makeconductive isolation switches 161, 163, and 165 to enable controller 121to receive signals on those signal lines from interface 115. In oneembodiment, the enable signal is asserted by controller 121 writing anenable value to an internal register (not shown) coupled to the ENABLEsignal line.

In operation 209, system controller 105 sends calibration configurationinformation on bus 113 to interface 115. Interface 115 stores theinformation in register 117 and the drives the configuration informationon CONFIGURATION lines to controller 121 in operation 211. Theconfiguration information will be used by controller 121 in performingmeasurements during the calibration mode.

In operation 213, system controller 105 writes to interface 115 acalibration start signal command on bus 113. In response, interface 115asserts the CALIBRATION START signal to controller 121 in operation 215.In one embodiment, interface 115 writes to an internal register coupledto the CALIBRATION START signal line a value indicative of an assertedCALIBRATION START signal.

In response to receiving the CALIBRATION START signal, controller 121reads the calibration information on the CONFIGURATION lines and storesthe information in configuration register 132 in operation 217. In oneembodiment, configuration register 132 is coupled to calibration module129 to control the operation of calibration module 129 during acalibration mode. In other embodiments, calibration module 129 reads theconfiguration information in register 132 during the calibration modeand then performs its operations accordingly. In one embodiment, thecalibration information indicates, for example, which sensors tomeasure, the noise filter parameters utilized, and the circuitcancellation measures implemented. In operation 219, controller 121deasserts the READY signal and the ENABLE signal to turn off isolationswitches 161, 163, and 165. In operation 221, module 129 starts thetemperature measurements of the calibration mode. In operation 223, theVDD1 power domain is powered down. In one embodiment, system controller105 polls a READY bit (not shown) in a register in interface 115 that isresponsive to the READY signal. Controller 105 then provides anindication to an external test system (not shown) that the VDD1 powerdomain can be powered down. The external test system then removes powerfrom the VDD1 terminal 141.

FIG. 3 is a state diagram showing the operation of controller 121 duringthe calibration mode. Controller 121 transitions into the calibrationmode state 301 by operation 221 (Shown in FIG. 2). In the calibrationstate 301, calibration module 129 continuously reads each sensor (137,139) and records the temperature data in data register 131. In oneembodiment, data register 131 has space to record a specific number ofmeasurements per sensor. In some embodiments, a time stamp may berecorded with each measurement. In one embodiment, the calibrationmodule keeps recording measurements continuously and rewriting over theoldest recorded measurement for a sensor with the most recentmeasurement. In one embodiment, the temperature measurements are madewhile the die is submerged in an oil bath that is at a specifiedtemperature. In one embodiment, the amount of time spent in thecalibration mode state is dependent upon the amount of time needed forthe die to reach the oil bath temperature after VDD1 is removed.

While the temperature measurements are being made, power has beenremoved from the VDD1 power domain. Accordingly, the temperature datarecorded is not affected by heat generated from the VDD1 power domaincircuitry.

In the embodiment shown, controller 121 remains in state 301 until theVDD1 READY signal is asserted indicating that VDD1 power domain is beingpowered up. In response, controller 121 goes into state 303 where itstops taking measurements and maintains the data in its data register131. Controller 121 then provides the data to the system controller viainterface 115 on the DATA lines upon request. In one embodiment, therequest is made via the CONFIGURATION signal lines, but may be made byother control signal lines (not shown) in some embodiments. In someembodiments, the DATA lines may include a DATA VALID signal to indicatethat controller 121 is transferring valid data. Also in state 303,controller 121 asserts the READY signal indicating that it is ready totake measurements.

As described above, module 129 continuously takes temperaturemeasurements until the assertion of the VDD1 READY signal. In otherembodiments, module 129 may include a counter to take a finite number ofmeasurements. In some embodiments, the number of measurements may be setby the configuration information.

The data information can be externally supplied from die 102 via theaccess terminals 171. In some embodiments, die 102 can be placed incalibration mode multiple times, each with the oil bath set at adifferent temperature. After each time, the data is downloaded fromsystem 101 and correlated with the temperature of the oil bath.

In some embodiments, voltage domain VDD1 may include a power switch (notshown) that is controlled by temperature monitoring system 104. Whencontroller 121 goes into a calibration mode, the power switch is openedto remove power to regulator 147. When a particular number ofmeasurements are made, controller 121 would close the power switch forpower to be supplied to regulator 147. However, an advantage of removingpower from terminal 141 during a calibration mode is that the leakagecurrent from an internal power switch would not affect the temperaturemeasurements during the calibration mode.

FIG. 4 is a flow diagram illustrating the operations in generatingtemperature calibration values from the measured temperature data madeduring a calibration mode. Some or all of these operations may beperformed by the system manufacturer, a purchaser of the system, an enduser manufacture, and/or by an end user system. In operation 403, themeasured temperature values made in the calibration mode are downloadedfrom system 101 (via the access terminals 171) to an analyzing systemsuch as a computer system of the system manufacture. The temperaturedata is then analyzed to determine calibration values that will be usedto adjust subsequently measured data made by a temperature monitoringsystem of a similarly designed die. In one embodiment, calibrationvalues are determined from an average of all sensor measurements foreach specific temperature. In one embodiment, at least two calibrationvalues are determined (e.g. for a minimum temperature and maximumtemperature) assuming a linear temperature curve. However, calibrationvalues for more than two temperatures can be determined in otherembodiments. In one embodiment, 9-bit calibration values can begenerated for temperatures of 200, 250, 350, and 450 degrees Kelvin(calibration temperature points).

In operation 407, the calibration data is then loaded into one or moresystems similar to system 101 and stored as data (108) of memory (107).In some embodiments, the data is stored in fuses or in another type ofone time programmable memory. After the systems (101) are sold tocustomers, the temperature monitoring systems (104) of each system areused to take temperature measurements at each of their sensors (137,139). When the measured temperature data is provided back to the systemcontroller (105), the system controller (105) uses the calibration data(108) to adjust the measured temperature data to provide a more accuratereading (see operation 409). The calibration values for temperaturesbetween the calibration temperature points can be determined byextrapolation by the system controller. In other embodiments, thecalibration data (108) would be stored in the temperature monitoringsystem (104) and would be used to adjust the measured temperature dataprior to being provided to the system controller (105).

In one embodiment, measured temperature data taken during a calibrationmode would be obtained from one integrated circuit die from a batch ofintegrated circuit die. The data obtained from the calibration mode ofthe one die would be used to generate calibration data and stored in therest of the integrated circuit die of the batch.

The temperature monitoring system 104 can also be used during theoperation of system controller 105 to gather temperature data during theuse of the system 101 by an end customer. FIG. 5 shows the operations ofsystem 101 when temperature monitoring system 104 is in a monitoringmode. Protocol 501 picks up from operation 207 of FIG. 2 where the VDD1READY and ENABLE signals are asserted.

In operation 503, controller 105 sends monitoring configurationinformation to interface 115 via bus 113. The monitoring configurationinformation indicates which temperature sensor system 101 would liketemperature data taken from. In operation 505, interface 115 drives themonitoring configuration data on the CONFIGURATION lines. In operation507, controller 105 writes to interface 115 a monitoring start command.In operation 509, interface 115 asserts the MONITORING START signal tocontroller 121. In operation 511, controller 121 reads the monitoringconfiguration information and stores the information in configurationregister 132. In operation 513, controller 121 takes the temperaturereading(s) as per the monitoring configuration information, stores thedata in data register 131, provides the data on the data signal lines tointerface 115, and asserts a data valid signal (which in one embodimentis a signal line on the DATA signal lines). In operation 517, interface115 provides the measured temperature data to system controller 105. Inoperation 519, system controller uses the calibration data 108 stored inmemory 107 to adjust the measured temperature data to provide a moreaccurate temperature data.

With the protocol set forth in FIG. 5, a system 101 is able to use thetemperature monitoring system 104 while system controller 105 is poweredand performing other functions. In other embodiments, system 104 maytake measurements from all sensors on the integrated circuit die 102 inresponse to a specific monitoring configuration information value and asingle assertion of the MONITORING START signal. In some embodiments,different locations of data register 131 may be read by specificconfiguration information values received from interface 115.

Other embodiments, may include other circuitry, other configurations,and/or other protocols for gathering temperature data during acalibration and/or monitoring mode. In other embodiments, the dataregister 131 may be external to controller 121 and may be readable byinterface 115. Also, the system may include other signal lines(including other control signal lines) other than those shown in FIG. 1.

Although the temperature monitoring system is described above asgathering temperature data in a “calibration” mode for generationcalibration values with the other circuitry of the die not receivingpower, in other embodiments, such a mode of operation can be used by anend user system to make temperature measurements where it is importantthat heat generated from the system controller and other circuitry ofthe VDD1 power domain does not affect the temperature measurements.

In one embodiment, an integrated circuit die includes a systemcontroller, at least one temperature sensor, and a temperaturemonitoring system. The temperature monitoring system is for obtainingmeasured temperature data from the at least one temperature sensor. Thetemperature monitoring system includes a module including circuitry. Themodule is configured to obtain measured temperature data from the atleast one temperature sensor in a mode performed when power is not beingprovided to the system controller.

In another embodiment, a method for obtaining measured temperature dataon an integrated circuit die includes operating a temperature monitoringsystem of the integrated circuit die in a first mode while a systemcontroller of the integrated circuit die is powered down. In the firstmode, the temperature monitoring system obtains measured temperaturedata from at least one sensor on the integrated circuit die and storesthe measured temperature data in a memory. The method includes poweringup the system controller, and after powering up the system controller,providing the measured temperature data to the system controller.

In other embodiment, a method for obtaining temperature data on anintegrated circuit die includes obtaining by a temperature monitoringsystem of a first integrated circuit die, measured temperature data fromat least one temperature sensor on the first integrated circuit die. Themethod includes adjusting the measured temperature data by at least onecalibration value. The at least one calibration value is developed fromtemperature measurements made by a temperature monitoring system of asecond integrated circuit die operating in a first mode while a systemcontroller of the second integrated circuit die is powered down. In thefirst mode, the temperature monitoring system of the second integratedcircuit die obtained the measured temperature data from at least onesensor on the second integrated circuit die. After being powered up, thesystem controller of the second integrated circuit die obtained themeasured temperature data. The second integrated circuit die is of asimilar design to the first integrated circuit die.

While particular embodiments of the present invention have been shownand described, it will be recognized to those skilled in the art that,based upon the teachings herein, further changes and modifications maybe made without departing from this invention and its broader aspects,and thus, the appended claims are to encompass within their scope allsuch changes and modifications as are within the true spirit and scopeof this invention.

What is claimed is:
 1. An integrated circuit die comprising: a systemcontroller; at least one temperature sensor; a temperature monitoringsystem, the temperature monitoring system for obtaining measuredtemperature data from the at least one temperature sensor, wherein thetemperature monitoring system includes a module including circuitry, themodule configured to obtain measured temperature data from the at leastone temperature sensor in a mode performed when power is not beingprovided to the system controller; wherein the temperature monitoringsystem includes an input to receive an indication of whether power isbeing provided to the system controller, wherein in the mode, the modulestops taking data in response to the indication changing from indicatingthat the system controller is not receiving power to an indication thatthe system controller is receiving power.
 2. The integrated circuit dieof claim 1 wherein in the mode, the module continuously obtains datafrom the at least one temperature sensor until receiving an indicationthat power is being supplied to the system controller.
 3. The integratedcircuit die of claim 1 wherein the system controller is located in afirst power domain of the integrated circuit die and the module islocated in a second power domain of the integrated circuit die.
 4. Theintegrated circuit die of claim 3 wherein the temperature monitoringsystem includes circuitry in the second power domain that receives asignal on a signal line from circuitry in the first power domain,wherein the signal line includes an isolation gate that isolates thecircuitry in the second power domain from the circuitry in the firstpower domain on the signal line.
 5. The integrated circuit die of claim3 wherein the integrated circuit die includes a first external powerterminal for receiving power to power the first power domain and asecond external power terminal for receiving power to power the secondpower domain.
 6. The integrated circuit die of claim 1 wherein thetemperature monitoring system includes a memory for storing measuredtemperature data, wherein the measured temperature data is available tothe system controller when not in the mode.
 7. The integrated circuitdie of claim 1 wherein the temperature monitoring system is capable ofobtaining measured temperature data from the at least one temperaturesensor when the system controller is powered up in a second mode ofoperation.
 8. A method for obtaining measured temperature data on anintegrated circuit die, the method comprising: operating a temperaturemonitoring system of the integrated circuit die in a first mode while asystem controller of the integrated circuit die is powered down, whereinin the first mode, the temperature monitoring system obtains measuredtemperature data from at least one sensor on the integrated circuit dieand stores the measured temperature data in a memory; powering up thesystem controller; after powering up the system controller, providingthe measured temperature data to the system controller; providing anindication to the temperature monitoring system that the systemcontroller is being powered up, wherein the temperature monitoringsystem exits the first mode and stops obtaining measured temperaturedata from the at least one sensor in response to receiving theindication.
 9. The method of claim 8 further comprising: prior to theoperating the temperature monitoring system in the first mode, providingan indication to the temperature monitoring system that the systemcontroller is being powered down, wherein the temperature monitoringsystem enters the first mode at least in response to receiving theindication.
 10. The method of claim 8, wherein the temperaturemonitoring signal receives a signal on a signal line from circuitry thatis powered up and is powered down with the system controller, whereinthe temperature monitoring system is isolated on the signal line fromthe circuitry that is powered up and is powered down with the systemcontroller when in the first mode.
 11. The method of claim 8, wherein inthe first mode, the temperature monitoring system continuously obtainsmeasured temperature data from the at least one sensor on the integratedcircuit die and stores the measured temperature data in the memory. 12.The method of claim 8 wherein the operating the temperature monitoringsystem in the first mode occurs when the integrated circuit die is in ahot oil bath.
 13. The method of claim 8 wherein the integrated circuitdie includes a first external power supply terminal that supplies powerfor the temperature monitoring system and a second external power supplyterminal that supplies power for the system controller, wherein power isnot supplied to the second external power supply terminal when thesystem controller is powered down in the first mode.
 14. A method forobtaining measured temperature data on an integrated circuit die, themethod comprising: operating a temperature monitoring system of theintegrated circuit die in a first mode while a system controller of theintegrated circuit die is powered down, wherein in the first mode, thetemperature monitoring system obtains measured temperature data from atleast one sensor on the integrated circuit die and stores the measuredtemperature data in a memory; powering up the system controller; afterpowering up the system controller, providing the measured temperaturedata to the system controller; after the providing the measuredtemperature data to the system controller, providing the measuredtemperature data to an external system; determining by the externalsystem, temperature calibration values from the measured temperaturedata.
 15. The method of claim 14 further comprising: loading thetemperature calibration values into a memory of a second integratedcircuit die, the second integrated circuit die including a systemcontroller and a temperature monitoring system, wherein the temperaturecalibration values are for adjusting by the second integrated circuitdie, measured temperature data made by the temperature monitoring systemof the second integrated circuit die.
 16. A method for obtainingtemperature data on an integrated circuit die, the method comprising:obtaining by a temperature monitoring system of a first integratedcircuit die, measured temperature data from at least one temperaturesensor on the first integrated circuit die; adjusting the measuredtemperature data by at least one calibration value, wherein the at leastone calibration value is developed from temperature measurements made bya temperature monitoring system of a second integrated circuit dieoperating in a first mode while a system controller of the secondintegrated circuit die is powered down, wherein in the first mode, thetemperature monitoring system of the second integrated circuit dieobtained the measured temperature data from at least one sensor on thesecond integrated circuit die, and after being powered up, the systemcontroller of the second integrated circuit die obtained the measuredtemperature data, wherein the second integrated circuit die is of asimilar design to the first integrated circuit die.
 17. The method ofclaim 16 wherein the adjusting is performed by a system controller ofthe first integrated circuit die.
 18. The method of claim 16 wherein theobtaining by temperature monitoring system of the first integratedcircuit die is performed while power is provided to a system controllerof the first integrated circuit die.
 19. A method for obtainingtemperature data on an integrated circuit die, the method comprising:obtaining by a temperature monitoring system of a first integratedcircuit die, measured temperature data from at least one temperaturesensor on the first integrated circuit die; adjusting the measuredtemperature data by at least one calibration value stored in a memory ofthe first integrated circuit die and developed from temperaturemeasurements made by a temperature monitoring system of a secondintegrated circuit die operating in a first mode while a systemcontroller of the second integrated circuit die is powered down, whereinin the first mode, the temperature monitoring system of the secondintegrated circuit die obtained the measured temperature data from atleast one sensor on the second integrated circuit die, and after beingpowered up, the system controller of the second integrated circuit dieobtained the measured temperature data, wherein the second integratedcircuit die is of a similar design to the first integrated circuit die.